Overview of Intracranial Tumors

There are 2 types of brain tumors:

Brain metastases are about 10 times more common than primary tumors.

Type of tumor varies somewhat by site (see table Common Localizing Manifestations of Primary Brain Tumors Common Localizing Manifestations of Primary Brain Tumors ) and patient age (see table Common Tumors by Age Common Brain Tumors by Age ).

Neurologic dysfunction may result from the following:

A malignant tumor can develop new internal blood vessels, which can bleed or become occluded, resulting in necrosis and neurologic dysfunction that mimics stroke. Bleeding as a complication of metastatic tumors is most likely to occur in patients with melanoma, renal cell carcinoma, choriocarcinoma, or thyroid, lung, or breast cancer.

Benign tumors grow slowly. They may become quite large before causing symptoms, partly because often there is no cerebral edema. Malignant primary tumors grow rapidly but rarely spread beyond the CNS. Death results from local tumor growth and/or tumor-related hemorrhage and thus can result from benign as well as malignant tumors.

Symptoms caused by primary tumors and metastatic tumors are the same. Many symptoms result from increased intracranial pressure:

Headache is the most common symptom. Headache may be most intense when patients awake from deep nonrapid eye movement (non-REM) sleep (usually several hours after falling asleep) because hypoventilation, which increases cerebral blood flow and thus intracranial pressure, is usually maximal during non-REM sleep. Headache is also progressive and may be worsened by recumbency or the Valsalva maneuver. When intracranial pressure is very high, the headache may be accompanied by vomiting, sometimes with little nausea preceding it.

Papilledema develops in about 25% of patients with a brain tumor but may be absent even when intracranial pressure is increased. In infants and very young children, increased intracranial pressure may enlarge the head. If intracranial pressure increases sufficiently, brain herniation Brain Herniation Brain herniation occurs when increased intracranial pressure causes the abnormal protrusion of brain tissue through openings in rigid intracranial barriers (eg, tentorial notch). Because the... read more occurs.

Deterioration in mental status is the 2nd most common symptom. Manifestations include drowsiness, lethargy, personality changes, disordered conduct, and impaired cognition, particularly with malignant brain tumors. Airway reflexes may be impaired.

Focal brain dysfunction causes some symptoms. Focal neurologic deficits, endocrine dysfunction, or focal seizures (sometimes with secondary generalization) may develop depending on the tumor’s location (see table ). Focal deficits often suggest the tumor’s location. However, sometimes focal deficits do not correspond to the tumor’s location. Such deficits, called false localizing signs, include the following:

Generalized seizures Seizure Disorders A seizure is an abnormal, unregulated electrical discharge that occurs within the brain’s cortical gray matter and transiently interrupts normal brain function. A seizure typically causes altered... read more may occur, more often with primary than metastatic brain tumors. Impaired consciousness Overview of Coma and Impaired Consciousness Coma is unresponsiveness from which the patient cannot be aroused and in which the patient's eyes remain closed. Impaired consciousness refers to similar, less severe disturbances of consciousness... read more can result from herniation, brain stem dysfunction, or diffuse bilateral cortical dysfunction.

Some tumors cause meningeal inflammation, resulting in subacute or chronic meningitis Subacute and Chronic Meningitis Subacute meningitis develops over days to a few weeks. Chronic meningitis lasts ≥ 4 weeks. Possible causes include fungi, Mycobacterium tuberculosis, rickettsiae, spirochetes, Toxoplasma... read more .

Early-stage brain tumors are often misdiagnosed. A brain tumor should be considered in patients with any of the following:

Similar findings can result from other intracranial masses (eg, abscess Brain Abscess A brain abscess is an intracerebral collection of pus. Symptoms may include headache, lethargy, fever, and focal neurologic deficits. Diagnosis is by contrast-enhanced MRI or CT. Treatment is... read more , aneurysm Brain Aneurysms Brain aneurysms are focal dilations in the cerebral arteries. In the US, brain aneurysms occur in 3 to 5% of people. Brain aneurysms can occur at any age but are most common among people aged... read more , arteriovenous malformation Cerebral Arteriovenous Malformations (AVMs) Arteriovenous malformation (AVMs) are tangled, dilated blood vessels in which arteries flow directly into veins. AVMs occur most often at the junction of cerebral arteries, usually within the... read more , intracerebral hemorrhage Intracerebral Hemorrhage Intracerebral hemorrhage is focal bleeding from a blood vessel in the brain parenchyma. The cause is usually hypertension. Typical symptoms include focal neurologic deficits, often with abrupt... read more , subdural hematoma Hematomas , granuloma, parasitic cysts such as neurocysticercosis Neurocysticercosis Parasitic helminthic worms infect the central nervous system (CNS) of millions of people in developing countries. Infected people who visit or immigrate to nonendemic areas, including the US... read more ) or ischemic stroke Ischemic Stroke Ischemic stroke is sudden neurologic deficits that result from focal cerebral ischemia associated with permanent brain infarction (eg, positive results on diffusion-weighted MRI). Common causes... read more .

A complete neurologic examination, neuroimaging, and chest x-rays (for a source of metastases) should be performed. T1-weighted MRI with gadolinium is the study of choice. CT with contrast agent is an alternative. MRI usually detects low-grade astrocytomas and oligodendrogliomas earlier than CT and shows brain structures near bone (eg, the posterior fossa) more clearly. If whole-brain imaging does not show sufficient detail in the target area (eg, sella turcica, cerebellopontine angle, optic nerve), closely spaced images or other special views of the area are obtained. If neuroimaging is normal but increased intracranial pressure is suspected, idiopathic intracranial hypertension Idiopathic Intracranial Hypertension Idiopathic intracranial hypertension causes increased intracranial pressure without a mass lesion or hydrocephalus, probably by obstructing venous drainage; cerebrospinal fluid composition is... read more should be considered and lumbar puncture Lumbar Puncture (Spinal Tap) Lumbar puncture is used to do the following: Evaluate intracranial pressure and cerebrospinal fluid (CSF) composition (see table Cerebrospinal Fluid Abnormalities in Various Disorders) Therapeutically... read more done.

Radiographic clues to the type of tumor, mainly location (see table ) and pattern of enhancement on MRI, may be inconclusive; brain biopsy, sometimes excisional biopsy, may be required.

Specialized tests (eg, molecular and genetic tumor markers in blood and cerebrospinal fluid [CSF]) can help in some cases. In patients with AIDS, Epstein-Barr virus titers in CSF typically increase as CNS lymphoma develops.

Patients in a coma or with impaired airway reflexes require endotracheal intubation Tracheal Intubation Most patients requiring an artificial airway can be managed with tracheal intubation, which can be Orotracheal (tube inserted through the mouth) Nasotracheal (tube inserted through the nose)... read more .

Brain herniation Brain Herniation Brain herniation occurs when increased intracranial pressure causes the abnormal protrusion of brain tissue through openings in rigid intracranial barriers (eg, tentorial notch). Because the... read more due to tumors is treated with hyperosmotic therapy (mannitol 25 to 100 g infused IV or 23.4 % hypertonic saline 20 mL infused through a central line and a corticosteroid [eg, dexamethasone 16 mg IV, followed by 4 mg orally or IV every 6 hours]) plus endotracheal intubation. Hyperventilation to a carbon dioxide partial pressure (PCO2) of 26 to 30 mm Hg can help decrease intracranial pressure temporarily in emergencies. Mass lesions should be surgically decompressed as soon as possible.

Increased intracranial pressure due to tumors but without herniation can be treated with corticosteroids (eg, dexamethasone 4 mg orally every 6 to 12 hours or prednisone 30 to 40 mg orally twice a day).

Treatment of the brain tumor depends on pathology and location. Surgical excision should be used for diagnosis (excisional biopsy) and symptom relief. It may cure benign tumors. For tumors infiltrating the brain parenchyma, treatment is multimodal. Radiation therapy is required, and chemotherapy, targeted therapy, and/or immunotherapy appears to benefit some patients.

Treatment of metastatic tumors includes radiation therapy and sometimes stereotactic radiosurgery. For patients with a single metastasis, surgical excision of the tumor before radiation therapy improves outcome.